The court heard the men, who all have alcohol problems, had been employed as “cutters” on £100 a day.

Robert Jackson said he had been taken on for three days and had been caught on the second day. He had become involved to pay off a loan shark debt.

Jason Smith, defending Paul Dawson, said his client was an alcoholic who had been drinking from a can of cider when he was arrested at 9.30am.

He said he was “at the bottom of the chain” and was there to makes a few pounds for himself.

Stephen Bird was described as a repairer of household goods who had fallen pray to temptation after the recession made his work dry up.

Judge Steven Everett, sentencing, accepted that the men were gardeners and not the organisers. He said that cannabis farms were on the increase because the sentences were lower relative to Class A drugs like heroin or cocaine.

He added: “The court has to send out a message to anyone getting involved in this sort of operation that a substantial sentence is necessary even for people like you who play a limited role.

“It sends out a message to you and others like you because if you decide it is an easy way of making money if caught you are going to prison for some time.

“The use of cannabis in this country is high and cannabis is an evil drug which brings nothing but harm to those who use it.”

Describing the factory Judge Everett said it had been producing cannabis on an industrial scale.

He said: “It must have taken a substantial amount of time to set up and it shows how sophisticated it was.”

All three men pleaded guilty to producing cannabis.

Robert Jackson, 53, of Breck Road, Everton and Paul Dawson, 51, of Prescot Road, Fairfield, were both jailed for three years. Stephen Bird, 52, of Longstone Walk, Edge Hill, was jailed for two years ten months.